This invention relates generally to office machines and specifically to a finishing station of an electrophotographic printing machine. More particularly, the present invention relates to a stapler system of such a machine.
In a typical electrophotographic printing process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet.
In a commercial printing machine of the foregoing type, it is often desirable to stack the discharged copy sheets, numbering from two sheets up to a large number of sheets, in sets with very close stack registration so as to avoid a ragged or uneven looking stack edge in finished, bound or stapled copy sets. It is further desirable when stapling or binding a set of sheets to so locate or move the stapling or binding device that it can act upon the stack without disturbing the stack registration.
It is known in such office machines to provide a stapler mechanism which staples the registered stack of sheets together. Such staplers can be mounted on a carriage which is moved along one of the edges, the bind edge, of the stack of sheets in order that such stapling can take place. However, in the conventionally known stapler systems associated with a compiler of a copier, the stapler is a separate mechanism that needs to be moved in and out in order to perform the stapling operation. Even in those staplers which are so positioned in relationship to the compiler as to not need a movement of the stapler in order to perform the stapling operation, the stapler if it is moved horizontally along the bind edge of the sheets needs to be moved in and out in order to get around obstacles provided on the machine itself. That is to say, in the known design of a stapler located at the compiler of a copier, the stapler assembly needs to move in two directions, (1) along the bind edge for multiple stapling positions and (2) in an up and back motion in the process direction to move around obstacles or to allow sheet set delivery.
In a very recently introduced product, a linear motion stapler is associated with a sorter device of a copier. In this product, each copy is fed to a different bin of the sorter. When the copying operation is over, the stack of sheets and the sorter tray in each bin is pulled back into the stapler apparatus by a set transport mechanism, is stapled, and is then returned to its bin. The sorter indexes every occupied bin in this fashion. Fixed back walls are secured to the stapler carriage to stop the movement of the set in the process direction. However, this product is a sorter in which the copies are fully supported in bins and not partially supported by a wall of the complier as in a finisher. In addition, in this product, the sheets are not compiled over a portion of the stapler and this would be advantageous to increase the speed with which the machine can operate. Finally, this design requires the use of a separate set transport mechanism as the sheets are not compiled right over the stapler.
Accordingly, it has been considered desirable to develop a new and improved stapler system for the single tray finishing station of an office machine which system would have a strictly linear motion and thereby overcome the foregoing difficulties and others while providing better and more advantageous overall results.